1. Field of the Invention
This invention relates to a color printer, fax machine, photocopier, or other image formation device which forms images using electrophotographic techniques, and in particular relates to an image formation device enabling switching of the developer remaining amount display in monochrome printing mode, for enhanced flexibility of management of development units in monochrome printing mode.
2. Description of the Related Art
Image formation devices which form images using electrophotographic technology, provided for example in color printers, have an image carrier in which is formed an electrostatic latent image according to image data; a charging unit which charges the outer surface of the image carrier; an exposure unit which exposes the outer surface of the charged image carrier according to image data, to form an electrostatic latent image; a developer device which supplies toner, as a developing agent, to the electrostatic latent image to develop a toner image; and a transfer unit which causes the toner image to be transferred to a media. The developer device detachably holds a plurality of developing units which house color toners, and has a developer unit holder which causes the appropriate developer unit to be brought into proximity with the image carrier according to the development timing. This developer unit holder is normally a rotatably controlled developing rotary. When the image formation device is in a color printing mode, development units with color toner in a plurality of colors, for example, four colors (yellow or Y, magenta or M, cyan or C, and black or K) is mounted in the developing rotary. When the image formation device is in a monochrome printing mode, such as black and white print mode, a black development unit is mounted in the developing rotary.
An image formation device has been proposed which can be put into a color printing mode in which a four-color development unit is mounted, or into a monochrome printing mode in which only a black development unit is mounted, with the user able to switch between the two modes as appropriate. Such an image formation device has been proposed in, for example, Japanese Patent Laid-open No. 2003-43773 (Publication Date: Feb. 14, 2003), Japanese Patent Laid-open No. 2003-316106 (Publication Date: Nov. 6, 2003), and Japanese Patent Application No. 2003-160059.
In Japanese Patent Laid-open No. 2003-43773 and Japanese Patent Application No. 2003-160059, an image formation device is disclosed in which the color printing mode is set when four color development units are mounted in the developing rotary, and the monochrome printing mode is set when a single black development unit is mounted only in the mounting position for the black development unit of the developing rotary, with no development units mounted in the other mounting positions, which are CMY positions.
In Japanese Patent Laid-open No. 2003-316106, an image formation device in which a black development unit is detachable at any mounting positions in the developing rotary is disclose. In this image formation device, information on the color of the developing agent is read from memory provided in the development unit, to detect which color development units are mounted in which positions of the developing rotary. Specifically, in Japanese Patent Laid-open No. 2003-316106, when development units in the four CMYK colors are mounted, the device operates as a color printer, and when only the black development unit is mounted, the device operates as a black monochrome printer. Further it is disclosed that the black development unit can be mounted with an arbitrary number among 1-4 units, and when plural development units being mounted, an exchange frequency of the development units can be restrained.
Further, an image formation device has been proposed in which, by mounting black development units in all four of the mounting positions of the developing rotary and setting the monochrome printing mode, the number of times development units need to be replaced can be reduced. Such an image formation device is disclosed in Japanese Patent Laid-open No. 2002-351190 (Publication Date: Dec. 4, 2002). In this image formation device, by mounting four black development units in the four mounting positions of the developing rotary for color printing, reading memory provided in the development units, detecting the mounting positions, color information, and amount of toner remaining, and by using the black development units in order, the frequency of replacement of development units in monochrome printing mode can be reduced, even for small-type development devices.
The image formation devices of Japanese Patent Laid-open No. 2003-43773 (Laid-open date: Feb. 14, 2003) and Japanese Patent Application No. 2003-160059 operate in color printing mode when development units in four colors (CMYK) are installed in the development rotary, and operate in monochrome printing mode when only a black development unit is installed in the black position of the development rotary. Hence in order to put the device into monochrome printing mode, the black development unit can only be installed in the black position, and installation of the black development unit in another position is not permitted; hence there is no flexibility or freedom in selecting the installation position for the black development unit, and so there is the problem that convenience to the user is decreased.
On the other hand, the image formation device of Japanese Patent Laid-open No. 2002-351190 (Laid-open date: Dec. 4, 2002), in monochrome printing mode, permits the installation of a development unit, in black or another single color, in an arbitrary position among the four development unit installation positions. However, there is no description of the method of display of the amount of toner remaining when a plurality of development units of the same color are installed, nor is there any description indicating how to improve convenience to the user through such a display.
The image formation device of Japanese Patent Laid-open No. 2003-316106 (Laid-open date: Nov. 6, 2003) also permits the installation of four black development units in four installation positions; but there is no description of the method of display to inform the user of the amount of toner remaining in this case.
When an image formation device is in monochrome printing mode, with increased freedom of installation of development units, the manner of display to the user of the amount of toner remaining in installed development units is important in order to enhance convenience to the user.